The present invention relates to the treatment of seed.
"Seed" means any plant member capable of resulting in the reproduction of a plant and obtained either by a sexual route, in which case it will be referred to as grain, or by vegetative reproduction, in which case it will be referred to as a plant or explant.
A treatment means any application of a liquid or solid product to the surface of the seed.
When this application results in a change in the shape of the seed, for example to permit mechanical sowing of individual seeds, then coating techniques are involved. These generally comprise, in a first stage, the deposition of an adhesive product onto the seed and then, optionally after partial drying, the deposition of a liquid charge or of a powder, a treatment agent, an agro-chemical product, a dye or other adjuvant which fertilizes or improves the germination conditions of the seed.
When this application is carried out without changing the shape of the seed, for example to provide protection, and, optionally, a colour or an appearance, then this will be referred to as film-coating. This technique comprises spraying the seed to form a deposit of a liquid, frequently aqueous, composition of a film-forming product containing a treatment agent, and simultaneously drying the deposit obtained.
These coating and film-coating techniques rely, among others, on rotary horizontal cylindrical drums comprising, besides the drum as such, means for driving it, means for distributing the charge and the treatment agent and, optionally, means for drying. To ensure homogenization of the treatment, it is known to provide stirring members inside the drum. However, despite a marked improvement in the quality of the coating, this is frequently insufficient on an industrial scale when, for example, seed of irregular shape is treated or when it is intended to produce a film coating requiring a deposit of high quality, that is to say of high uniformity, over the entire surface of the seed, for protection and/or for colouring.
There is therefore a need to make it possible to carry out these treatments for protection and for improved appearance of these seeds, in order to improve the efficiency during the sowing.